Cyanoethylation of wool



United States Patent F CYANOETHYLATION 0F WOOL Norbert M. Bikales, Stamford, Conn., assignor to American Cyanamid Company, New York, N.Y., a corporation of Maine No Drawing. Application March 8, 1956 Serial No. 570,216

5 'Claims. (Cl. 8-1216 This invention relates to a process of cyanoethylating wool and to a new cyanoethylated wool produced thereby.

In the past ccllulosic fibers have been improved by introducing cyanoethyl groups, and particularly cyanoethylation of cotton has produced a product of'improved properties such as resistance to microbiological attack. In the cyanoethylation of cellulose caustic alkali is used in the reaction either concurrently with acrylonitrile or in a two-bath process in which the cotton is first treated with a bath containing the alkali and then with a bath of acrylonitrile.

When it was attempted to cyanoethylate proteins some success was achieved with various casein compositions by a modified procedure using very dilute aqueous alkali and a small amount of dilute acrylonitrile. In the case of wool, the ordinary cyanoethylation reaction conditions resulted in so much damage to the wool that no practically useful result was obtained. An attempt was made to react wool under the conditions used with casein, There was some weight increase of 0.7% but no practically useful product resulted.

According to the present invention it has been found that by a very special procedure a cyanoethylated wool of practical usefulness can be obtained. In the first place, an aqueous caustic soda solution is used having a concentration of from 0.001 to 0.4%. The amount of the solution should not exceed five times the weight of the wool treated. The acrylonitrile used should be greater than 50% of the weight of the wool and can be much more, the upper limit being merely a practical one of cost and handling bulk. The temperature of reaction is not significantly different from that used in the cyanoethylation of cotton, an advantageous range being from 50 to 80 C.

The process may be effected either as a two-bath process in which the wool is first treated with the dilute caustic alkali solution, which may advantageously be at a lower temperature such as room temperature, followed by removal of excess solution and reaction with acrylonitrile. When this two-bath process is used it should be noted that the statements made above with regard to the maximum amount of caustic alkali solution are based on the amount which is retained by the wool after treatment with the caustic alkali and removal of excess solution, for example by centrifuging. This is sometimes referred to in the art of cyanoethylation of cotton as wet pick-up and is expressed in a percentage of the weight of the material under cyanoethylation. It is also possible to contact the wool with caustic alkali and acrylonitrile below reaction temperatures and then raising the temperature to reaction temperature, a socalled single-bath process.

The cyanoethylated wool produced by the present invention and which has an increase in nitrogen percentage of at least 0.4%, which corresponds to a weight increase of approximately 1 /z% has important advantageous properties in that there is a very marked increase in dyeability with acid dyes. Thus, for example, when 2,890,925 Patented June 16, :1959,

. 2 two woolen fabrics one of which has been cyanoethylated by the present invention are dyed fromstandard baths of acid dyes the exhaustion of the bath in. the case of the cyanoethylated wool is very much faster and is more complete resulting in a deeper shade. Within wide limits the increased speed of exhaustion and increased depth of shade are roughly proportional to the degree of cyanoethylation.

The uniformly improved speed of exhaustion and deeper shades obtainable with aciddyes on cyanoethylated wool differs sharply from the dyeability changes with cyanoethylated cotton. There certain direct dyes, which dye untreated cotton well, do not dye cyanoethylated cotton at all or dye it in much weaker shades. With certain other dyes there is no significant diiference. Light fastness is also quite variable. Cyanoethylation of cotton is noted not for any uniformly increased dyeability but for the greater resistance to microbiological attack, conferring almost complete mildewproofness with 3.5 or more percent nitrogen, together with improved physical properties such as strength, abrasion and heat resistance and the like. It is not known why cyanoethylation of wool does not have any significant effect on resistance to microbiological attack but does confer markedly improved dyeability with acid dyes. No theoretical explanation of this greatly different behavior is advanced.

When the process of the present invention is to be used in dyeing wool yarn this may be effected advantageously as in the case of cottonyarn in package dyeing machines, and it is significant that there is no sub stantial difference in the operating technique when cyanoethylating wool than in the case of cotton although of course the concentrations of reagents are quite different. Wool fabric may advantageously be cyanoethylated in suitable equipment but for convenience .in the examples to follow the flannel cyanoethylations were effected in a laboratory package dyeing machine so as to maintain strictly comparable reaction conditions. Of course, the use of a package dyeing machine on a large scale is not economically desirable in the treatment of fabric.

In the following specific examples which illustrate the invention the parts are by weight unless otherwise specified. a

EXAMPLE 1 Worsted yarn 42/2 was wound on the perforated tube of a Gaston County Package Dyeing Machine of one pound capacity. Aqueous sodium hydroxide of 0.12% concentration was circulated through the package dyeing machine until the wool had taken up a uniform amount of the solution. The yarn was then centrifuged to a 208% wet pick-up, acrylonitrile introduced and the temperature raised to 60 C. at which temperature the package dyeing machine was operated until cyanoethylation was substantially complete, which in the laboratory machine took approximately one hour. The alkalinity was then neutralized with acetic acid and the yarn washed with water. Initially the yarn analyzed 16.46 weight percent total nitrogen, on a dry basis, and after cyanoethylation contained 17.08% nitrogen on the same basis. This represented an increase of 0.62% nitrogen which corresponds to a weight increase of 2.4%. The color, and dry and wet tensile strength of the wool were essentially unchanged by the treatment, but the dyeability with acid dyes is greatly increased.

EXAMPLE 2 of about 1.3%. However, the color of the wool had turned Somewhat yellow, and the wet tensile strength was poorer than the control which indicated some damage to the wool. It will be apparent that at the preferred temperatureused in this example, the upper limit of alkali concentration was; beginning to show poorer results.

The physical properties of the products of Examples 1 and 2 when compared with an untreated sample of the same wool as a control are shown in the following table where the dry tests were made at 21 C. and 65% relative humidity. The wet tests were made at the same temperature.

A square yard of 8 ounce Wool flannel was folded over the perforated package tube and treated with 0.15% NaOH and acrylonitrile as in Example 1. A wet pickup of 209% was obtained. The original fabric showed a total nitrogen percentage of 16.16 and after cyanoethylation 17.03%, both on a dry basis. This represents an increase of 0.87% nitrogen corresponding to a weight increase of 3.3% The color of the fabric was unaffected. When dyed with acid dyes in two identical baths using untreated fabric as a control, the treated fabric exhausted faster and produced a much deeper shade. 1 In Examples 1 and 3 above, and even in Example 2, there is no substantial destruction of the disulfide linkages in the wool. .The present invention should not be confused with the treatment of degraded wool in which the disulfide linkages have been reduced to sulfhydryl groups. This degraded wool has not produced a practically useful product with acrylonitrile. v

The increased elongation which is shown in the table following Examples; 1 and 2 is an important property with fabrics which have to adjust themselves under stress, such as slip covers and the like. Wherever increased elongation is desirable, the products of the present invention have improved properties in addition to their enhanced dyeability.

I claim:

1. A process of cyanoethylating wool which comprises: determining a weighf'of wool to be treated; forming an aqueous caustic alkali solution having a concentration of from 0.001% to 0.4% treating said weight of wool with said solution and acrylonitrile, the amount of solution being sufficient to wet said weight of wool, but not more thanfive times said weight and the amount of acrylonitrile being at least one-half said weight of wool, whereby the total nitrogen weight percent content of said wool is increased; and continuing said treatment until reaction substantially ceases and said total weight percent of nitrogen is at least 0.4% higher than that of the Wool before treatment. i

2. A process according to claim 1 in which the wool is first treated with the caustic alkali solution below reaction temperature, excess solution mechanically removed, and reaction with acrylonitrile then carried out at reaction temperature.

3. A process according to claim 1 in which the caustic alkali is sodium hydroxide. I

4. A process of cyanoethylating wool of which the disulfide linkages are substantially untransformed into sulthydryl groups which comprises subjecting the wool to the reaction of not more than 5 times its weight of caustic alkali solution of a concentration higher than 0.001% but not exceeding 0.4%, and acrylonitrile, the weight of which is at least equal to half the weight of the wool, until cyanethylation has proceeded to a point at which the increase in nitrogen percent is at least 0.4%.

5. Cyanoethylated wool prepared by: determining a weightof wool to be treated; forming an aqueous caustic alkali solution having a concentration of from 0.001%

to 0.4% treating said weight of Wool with said solution and acrylonitrile, the amount of solution being suflicient to wet said weight of wool, but not more than five times said weight and the amount of acrylonitrile being at least one-half said weight of wool, whereby the total nitrogen weight percent content of said wool is increased; and continuing said treatment until reaction substantially ceases and said total weight percent of nitrogen is at least 0.4% higher than that of the wool before treatment. 

1. A PROCESS OF CYANOETHYLATING WOOL WHICH COMPRISES: DETERMINING A WEIGHT OF WOOL TO BE TREATED; FORMING AN AQUEOUS CAUSTIC ALKALI SOLUTION HAVING A CONCENTRATION OF FROM 0.001% TO 0.4% TREATING SAID WEIGHT OF WOOL WITH SAID SOLUTION AND ACRYLONITRILE, THE AMOUNT OF SOLUTION BEING SUFFICIENT TO WET SAID WEIGHT OF WOOL, BUT NOT MORE THAN FIVE TIMES SAID WEIGHT AND THE AMOUNT OF ACRYLONITRILE BEING AT LEAST ONE-HALF SAID WEIGHT OF WOOL, WHEREBY THE TOTAL NITROGEN WEIGHT PERCENT CONTENT OF SAID WOOL IS INCREASED; AND CONTINUING SAID TREATMENT UNTIL REACTION SUBSTANTIALLY CEASES AND SAID TOTAL WEIGHT PERCENT OF NITROGEN IS AT LEAST 0.4% HIGHER THAN THAT OF THE WOOL BEFORE TREATMENT. 